Mechanical properties investigation of Si{sub 3}N{sub 4} ceramics
Book
·
OSTI ID:55409
- North Carolina A and T State Univ., Greensboro, NC (United States). Dept. of Mechanical Engineering
Significant progress has been made in the recent years in developing sintered silicon nitride structural ceramics for heat engine applications due to their excellent high temperature mechanical properties. Pure uniaxial tensile tests were conducted on a hot isostatically pressed (GTE PY6) and a sintered (GTE SNW-1000) silicon nitride ceramic at room and at elevated temperatures indicated that the tensile strength of this material dropped significantly after 900 C. The drop in the tensile strength for GTE SNW-1000 was much more pronounced compared to GTE PY6. Studies showed that precycling improved significantly the high temperature tensile strength in GTE SNW-1000. Precycling at elevated temperature led to nearly complete crystallization of the amorphous phases at the multi-grain junctions which is thought to be a reason for the observed improvement in tensile strength. The high temperature mechanical behavior was found to be controlled by the presence of amorphous phases along grain boundaries and multi-grain junctions. Tensile creep tests performed on GTE PY6 at 1,200 and 1,300 C showed that the steady state creep rate was influenced by both the temperature and the applied stress. The higher stress exponent in hot isostatically pressed (HIPed) as compared to a sintered silicon nitride shows higher creep resistance in the case of HIPed materials.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 55409
- Report Number(s):
- CONF-9310328--; ISBN 1-56676-232-4
- Country of Publication:
- United States
- Language:
- English
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